Process prints silicon on plastic

July 28/August 4, 2004

Many research groups are working to produce
flexible electronics. Most of those groups are working to improve the
electrical capabilities of organic, or plastic, materials.

Researchers from the University of Illinois at Urbana-Champaign
are taking a different tack. They are finding ways to produce extremely
small electrical components from crystalline silicon that can be attached
to a plastic backing.

Traditional silicon components have much better electrical properties
than organic ones. The components could be used in flexible large-area
displays, radiofrequency ID tags, sensors, and flexible, high-performance
applications like reconfigurable antennas, according to the researchers.

The researchers formed microscale or nanoscale components, including
ribbons, wires, platelets and disks from silicon wafers, then removed
the silicon from the insulating substrate, or base. They have developed
two methods to transfer the tiny, single-crystal components to a plastic
surface.

One method involves using rubber stamps to transfer the silicon
structures to a plastic substrate. The second calls for suspending the
structures in a liquid solvent, then depositing the liquid on a plastic
substrate.

Once the silicon is on plastic, the researchers form contacts
between components to make transistors. The transistors are much more
powerful than today's organic electronics, producing 180 square centimeter
per volt second rather than around 1.

The method could be used to produce commercial products within
two to three years, according to the researchers. The work appeared in
the June 28, 2004 issue of Applied Physics Letters.